The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. According to a first aspect the invention relates to a foldable bag that can be unfolded from an essentially flat initial state into an unfolded final state, provided with at least a first, a second and a third sheet for forming, respectively, a first, a second and a third wall of the foldable bag, wherein the first sheet is joined to the second sheet via the third sheet, which third sheet in the initial state is folded along a fold line, wherein the fold line of the third sheet in the initial state is between the first and the second sheet and wherein the foldable bag has at least one opening for filling and/or emptying the foldable bag.
A bag according to the preamble is known in the state of the art. The known bag is, for example, used for transporting, for example, fluids and paste-like products. The foldable bag is usually used in combination with a cube-shaped housing, such as a holder or a container, the top of which is open. The bag is placed in the housing in the folded state and then filled with a product via an opening in the wall of the bag. As a consequence of this the bag will unfold and fill the space in the housing. The filled bag is supported by the walls of the housing. The filled bag is transported together with the housing to the end user. The end user empties the bag and throws it away. The housing can be re-used.
The known bags, which are also termed pillow bags, generally consist of two rectangular sheets lying on top of one another which are joined to one another at the edges. The bag furthermore also has a first opening for filling the bag and optionally also a second opening for emptying the bag. Since the bag in the filled state is not cube shaped, bags must be used which have an internal volume in the filled state that is much greater than the internal volume of the housing. This is needed to ensure that the housing can be filled to the optimum possible extent. Before the bag is filled, the bag is draped over the housing or stuffed in the housing. Consequently an unnecessarily large amount of material is needed to produce these bags.
When such bags are emptied by means of suction it is possible that product that is in folds and/or corner points of the bag does not come out with the rest. When emptying the bag by means of suction it is also possible that a so-called collapse occurs. In this case part of the wall that is directly opposite the opening is sucked against the opening on the inside. This phenomenon occurs in particular once the bag has been sucked virtually empty. As a result the opening is closed off and no further product can leave the bag.
In the state of the art it is known to use foldable bags for transporting pastes or creams. When emptying by means of suction a few percent can be left in the bag. Bags are known which can take 1000 kg of paste or cream. If the paste or cream has a high price per kilogram, the portion that is left in the bag in the bag can represent a high value. Moreover, the material of such a bag in which the paste or cream is left is designated chemical waste. If better emptying of the bag were to be possible, the bag could be disposed of as ordinary waste.
As far as patent publications are concerned, reference can be made to U.S. Pat. No. 6,062,431; U.S. Pat. No. 5,788,121; U.S. Pat. No. 5,988,422 and DE-U 93.16.20.
U.S. Pat. No. 6,062,431 discloses a combination of a cardboard box with a bag for a fluid therein. This bag is of undefined shape and has a tap and filler cap. The filler cap is concealed under the lid of the box and the tap is in the box so that it can be pulled out from the box if tapping is desired.
U.S. Pat. No. 5,788,121 discloses a foldable bag made up of a first and second sheet with a folded third and fourth sheet between them, the fold lines of the latter facing one another. The sheets are joined to one another at the bottom and top by means of oblique seals in such a way that in the filled state the bag has a block shape, the fill/tap opening being provided in the top face of the block shape.
U.S. Pat. No. 5,988,422 discloses a foldable bag similar to that in U.S. Pat. No. 5,788,122. Here fill/tap openings are provided in both the top face and the bottom face of the block shape. DE-U 93.1620 discloses a foldable bag with a first, a second, a third and a fourth sheet, just as described in U.S. Pat. No. 5,788,122. In this case, however, the design is not such that the bag is block-shaped in the filled state; rather, it is tubular.